The interior of the climatic cabinet is, as a rule, accessible through a door, which is large enough, so as to set up a holding rack in the interior and to take it out of the interior. Furthermore, the interior can be cleaned and maintained through the door.
The holding rack is preferably loaded with specimen slides automatically with the aid of a suitable transporting device. Since the opening of the large main door would lead to sensitive disturbances of the climatic conditions in the interior, it has been proposed that a separate air lock be used for the loading and unloading of the specimen slides, which has the smallest possible passage cross-section and is only just large enough, so as to bring the specimen slides into the interior with the aid of the transporting device and to bring them out from the interior. Since only a very small opening in the outer wall of the climatic cabinet must be unblocked for the transporting of the specimen slides back and forth, the effects on the climatic conditions in the interior are clearly less and a continuous operation of the climatic cabinet without serious disturbances of the climate in the interior is possible.
Such a device is described, for example, in WO 98/05753 A1. The climatic cabinet described there has, in addition to a main door in the opposite, back wall, another smaller opening, which is used to transport specimen slides in and out of the interior. The smaller back opening, which is designated as a window opening, can be closed with a door. One or more carousels are used as a holding rack for the specimen slides in the interior of the climatic cabinet.
By using the reduced window opening in transporting specimen slides into the climatic chamber or out of it, the effects of the outside atmosphere on the interior can be clearly reduced, but not completely eliminated. Thus, when the small window is opened, there is also a certain exchange of the atmosphere and an influence on the temperature. Usually, that is the limit to the disturbance. In some special cases, however, there may be an impairment of the climate in the interior of the climatic cabinet. If, for example, the climatic cabinet is used as a climatic cooling cabinet, a small quantity of moisture is dragged in from the surrounding atmosphere into the interior of the climatic chamber every time a specimen slide is transported in. The moisture accumulates gradually in the interior and condenses or freezes because of the reduced temperature in the interior. If the moisture on specimen slides condenses or freezes, then this can lead to damage to the microorganisms or cell cultures and to a contamination of the specimens.
U.S. Pat. No. 6,467,285 B2 describes a climatic cooling cabinet, which is very similar to the apparatus of WO 98/05753 A1. The climatic cooling cabinet has a carousel to hold specimen slides in its interior, which are automatically transported into the interior with a transporting device and again conveyed out of it. Also, the transport does not take place here through the main door of the climatic cabinet, but rather through a smaller transporting air lock. There is a difference from WO 98/05753 A1 here, however, in that the air lock is constructed as a chamber, which can be closed on both sides, both with respect to the interior of the climatic cabinet and to its outside and which can be climatized itself alone. In order to move a specimen slide into the interior of the apparatus, the outer door of the air lock chamber is first opened, and the specimen slide is pushed into the air lock chamber while the inner door of the air lock chamber is closed. Then, the outer door of the air lock chamber is also closed, and a dry gas is introduced into the air lock chamber from a single inlet, which empties into an upper, inner section of the chamber, so as to expel the moisture from the air lock chamber and cool it. Subsequently, the inner door of the air lock chamber is opened, and the specimen slide is transported from the air lock chamber to the carousel and laid there. To transport the specimen slide from the climatic cooling cabinet, the steps are carried out in the reverse sequence. By means of the measures described, the influence on the climate in the interior of the climatic cooling cabinet by the outside atmosphere is reduced even more than in the case of WO 98/05753 A1. The apparatus, however, is constructed in a rather complicated manner and the transporting of each specimen slide takes a relatively long time, since the specimen slide must spend a longer period of time in the air lock chamber, until the dry gas has completely displaced the atmosphere in the air lock chamber.